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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package protodesc provides functionality for converting
// FileDescriptorProto messages to/from protoreflect.FileDescriptor values.
//
// The google.protobuf.FileDescriptorProto is a protobuf message that describes
// the type information for a .proto file in a form that is easily serializable.
// The protoreflect.FileDescriptor is a more structured representation of
// the FileDescriptorProto message where references and remote dependencies
// can be directly followed.
package protodesc
import (
"google.golang.org/protobuf/internal/errors"
"google.golang.org/protobuf/internal/filedesc"
"google.golang.org/protobuf/internal/pragma"
"google.golang.org/protobuf/internal/strs"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/reflect/protoregistry"
"google.golang.org/protobuf/types/descriptorpb"
)
// Resolver is the resolver used by NewFile to resolve dependencies.
// The enums and messages provided must belong to some parent file,
// which is also registered.
//
// It is implemented by protoregistry.Files.
type Resolver interface {
FindFileByPath(string) (protoreflect.FileDescriptor, error)
FindDescriptorByName(protoreflect.FullName) (protoreflect.Descriptor, error)
}
// FileOptions configures the construction of file descriptors.
type FileOptions struct {
pragma.NoUnkeyedLiterals
// AllowUnresolvable configures New to permissively allow unresolvable
// file, enum, or message dependencies. Unresolved dependencies are replaced
// by placeholder equivalents.
//
// The following dependencies may be left unresolved:
// • Resolving an imported file.
// • Resolving the type for a message field or extension field.
// If the kind of the field is unknown, then a placeholder is used for both
// the Enum and Message accessors on the protoreflect.FieldDescriptor.
// • Resolving an enum value set as the default for an optional enum field.
// If unresolvable, the protoreflect.FieldDescriptor.Default is set to the
// first value in the associated enum (or zero if the also enum dependency
// is also unresolvable). The protoreflect.FieldDescriptor.DefaultEnumValue
// is populated with a placeholder.
// • Resolving the extended message type for an extension field.
// • Resolving the input or output message type for a service method.
//
// If the unresolved dependency uses a relative name,
// then the placeholder will contain an invalid FullName with a "*." prefix,
// indicating that the starting prefix of the full name is unknown.
AllowUnresolvable bool
}
// NewFile creates a new protoreflect.FileDescriptor from the provided
// file descriptor message. See FileOptions.New for more information.
func NewFile(fd *descriptorpb.FileDescriptorProto, r Resolver) (protoreflect.FileDescriptor, error) {
return FileOptions{}.New(fd, r)
}
// NewFiles creates a new protoregistry.Files from the provided
// FileDescriptorSet message. See FileOptions.NewFiles for more information.
func NewFiles(fd *descriptorpb.FileDescriptorSet) (*protoregistry.Files, error) {
return FileOptions{}.NewFiles(fd)
}
// New creates a new protoreflect.FileDescriptor from the provided
// file descriptor message. The file must represent a valid proto file according
// to protobuf semantics. The returned descriptor is a deep copy of the input.
//
// Any imported files, enum types, or message types referenced in the file are
// resolved using the provided registry. When looking up an import file path,
// the path must be unique. The newly created file descriptor is not registered
// back into the provided file registry.
func (o FileOptions) New(fd *descriptorpb.FileDescriptorProto, r Resolver) (protoreflect.FileDescriptor, error) {
if r == nil {
r = (*protoregistry.Files)(nil) // empty resolver
}
// Handle the file descriptor content.
f := &filedesc.File{L2: &filedesc.FileL2{}}
switch fd.GetSyntax() {
case "proto2", "":
f.L1.Syntax = protoreflect.Proto2
case "proto3":
f.L1.Syntax = protoreflect.Proto3
default:
return nil, errors.New("invalid syntax: %q", fd.GetSyntax())
}
f.L1.Path = fd.GetName()
if f.L1.Path == "" {
return nil, errors.New("file path must be populated")
}
f.L1.Package = protoreflect.FullName(fd.GetPackage())
if !f.L1.Package.IsValid() && f.L1.Package != "" {
return nil, errors.New("invalid package: %q", f.L1.Package)
}
if opts := fd.GetOptions(); opts != nil {
opts = proto.Clone(opts).(*descriptorpb.FileOptions)
f.L2.Options = func() protoreflect.ProtoMessage { return opts }
}
f.L2.Imports = make(filedesc.FileImports, len(fd.GetDependency()))
for _, i := range fd.GetPublicDependency() {
if !(0 <= i && int(i) < len(f.L2.Imports)) || f.L2.Imports[i].IsPublic {
return nil, errors.New("invalid or duplicate public import index: %d", i)
}
f.L2.Imports[i].IsPublic = true
}
for _, i := range fd.GetWeakDependency() {
if !(0 <= i && int(i) < len(f.L2.Imports)) || f.L2.Imports[i].IsWeak {
return nil, errors.New("invalid or duplicate weak import index: %d", i)
}
f.L2.Imports[i].IsWeak = true
}
imps := importSet{f.Path(): true}
for i, path := range fd.GetDependency() {
imp := &f.L2.Imports[i]
f, err := r.FindFileByPath(path)
if err == protoregistry.NotFound && (o.AllowUnresolvable || imp.IsWeak) {
f = filedesc.PlaceholderFile(path)
} else if err != nil {
return nil, errors.New("could not resolve import %q: %v", path, err)
}
imp.FileDescriptor = f
if imps[imp.Path()] {
return nil, errors.New("already imported %q", path)
}
imps[imp.Path()] = true
}
for i := range fd.GetDependency() {
imp := &f.L2.Imports[i]
imps.importPublic(imp.Imports())
}
// Handle source locations.
for _, loc := range fd.GetSourceCodeInfo().GetLocation() {
var l protoreflect.SourceLocation
// TODO: Validate that the path points to an actual declaration?
l.Path = protoreflect.SourcePath(loc.GetPath())
s := loc.GetSpan()
switch len(s) {
case 3:
l.StartLine, l.StartColumn, l.EndLine, l.EndColumn = int(s[0]), int(s[1]), int(s[0]), int(s[2])
case 4:
l.StartLine, l.StartColumn, l.EndLine, l.EndColumn = int(s[0]), int(s[1]), int(s[2]), int(s[3])
default:
return nil, errors.New("invalid span: %v", s)
}
// TODO: Validate that the span information is sensible?
// See https://github.com/protocolbuffers/protobuf/issues/6378.
if false && (l.EndLine < l.StartLine || l.StartLine < 0 || l.StartColumn < 0 || l.EndColumn < 0 ||
(l.StartLine == l.EndLine && l.EndColumn <= l.StartColumn)) {
return nil, errors.New("invalid span: %v", s)
}
l.LeadingDetachedComments = loc.GetLeadingDetachedComments()
l.LeadingComments = loc.GetLeadingComments()
l.TrailingComments = loc.GetTrailingComments()
f.L2.Locations.List = append(f.L2.Locations.List, l)
}
// Step 1: Allocate and derive the names for all declarations.
// This copies all fields from the descriptor proto except:
// google.protobuf.FieldDescriptorProto.type_name
// google.protobuf.FieldDescriptorProto.default_value
// google.protobuf.FieldDescriptorProto.oneof_index
// google.protobuf.FieldDescriptorProto.extendee
// google.protobuf.MethodDescriptorProto.input
// google.protobuf.MethodDescriptorProto.output
var err error
sb := new(strs.Builder)
r1 := make(descsByName)
if f.L1.Enums.List, err = r1.initEnumDeclarations(fd.GetEnumType(), f, sb); err != nil {
return nil, err
}
if f.L1.Messages.List, err = r1.initMessagesDeclarations(fd.GetMessageType(), f, sb); err != nil {
return nil, err
}
if f.L1.Extensions.List, err = r1.initExtensionDeclarations(fd.GetExtension(), f, sb); err != nil {
return nil, err
}
if f.L1.Services.List, err = r1.initServiceDeclarations(fd.GetService(), f, sb); err != nil {
return nil, err
}
// Step 2: Resolve every dependency reference not handled by step 1.
r2 := &resolver{local: r1, remote: r, imports: imps, allowUnresolvable: o.AllowUnresolvable}
if err := r2.resolveMessageDependencies(f.L1.Messages.List, fd.GetMessageType()); err != nil {
return nil, err
}
if err := r2.resolveExtensionDependencies(f.L1.Extensions.List, fd.GetExtension()); err != nil {
return nil, err
}
if err := r2.resolveServiceDependencies(f.L1.Services.List, fd.GetService()); err != nil {
return nil, err
}
// Step 3: Validate every enum, message, and extension declaration.
if err := validateEnumDeclarations(f.L1.Enums.List, fd.GetEnumType()); err != nil {
return nil, err
}
if err := validateMessageDeclarations(f.L1.Messages.List, fd.GetMessageType()); err != nil {
return nil, err
}
if err := validateExtensionDeclarations(f.L1.Extensions.List, fd.GetExtension()); err != nil {
return nil, err
}
return f, nil
}
type importSet map[string]bool
func (is importSet) importPublic(imps protoreflect.FileImports) {
for i := 0; i < imps.Len(); i++ {
if imp := imps.Get(i); imp.IsPublic {
is[imp.Path()] = true
is.importPublic(imp.Imports())
}
}
}
// NewFiles creates a new protoregistry.Files from the provided
// FileDescriptorSet message. The descriptor set must include only
// valid files according to protobuf semantics. The returned descriptors
// are a deep copy of the input.
func (o FileOptions) NewFiles(fds *descriptorpb.FileDescriptorSet) (*protoregistry.Files, error) {
files := make(map[string]*descriptorpb.FileDescriptorProto)
for _, fd := range fds.File {
if _, ok := files[fd.GetName()]; ok {
return nil, errors.New("file appears multiple times: %q", fd.GetName())
}
files[fd.GetName()] = fd
}
r := &protoregistry.Files{}
for _, fd := range files {
if err := o.addFileDeps(r, fd, files); err != nil {
return nil, err
}
}
return r, nil
}
func (o FileOptions) addFileDeps(r *protoregistry.Files, fd *descriptorpb.FileDescriptorProto, files map[string]*descriptorpb.FileDescriptorProto) error {
// Set the entry to nil while descending into a file's dependencies to detect cycles.
files[fd.GetName()] = nil
for _, dep := range fd.Dependency {
depfd, ok := files[dep]
if depfd == nil {
if ok {
return errors.New("import cycle in file: %q", dep)
}
continue
}
if err := o.addFileDeps(r, depfd, files); err != nil {
return err
}
}
// Delete the entry once dependencies are processed.
delete(files, fd.GetName())
f, err := o.New(fd, r)
if err != nil {
return err
}
return r.RegisterFile(f)
}